A wind turbine typically comprises a rotor provided with a set of blades, wherein the rotor is arranged on top of a wind turbine tower anchored to a foundation embedded in the ground. Typically, the tower is made of steel, whereas the foundation is made of reinforced concrete. In order to anchor the steel tower to the concrete foundation, a flange with through-holes is provided at the bottom of the steel tower. Anchor bolts, embedded in the concrete foundation and protruding from the surface thereof, may then be introduced into the through-holes in the flange so that the flange may be fastened with nuts.
An alternative to using bolts embedded in the concrete is to utilize replaceable through-bolts which are arranged in through-holes in the concrete foundation.
An example of such an arrangement is found in US2007/0251187, which discloses a wind turbine foundation with an internal workspace for allowing inspection and maintenance of the through-bolts and the nuts securing the through-bolts to the foundation. The foundation according to US2007/0251187 includes an entrance which provides access to the workspace from the interior of the tower.
Although enabling inspection of the through-bolts, there appears to be room for improvement with regards to the structural strength of the foundation disclosed in US2007/0251187.